In deep sea divers, decompression illness is mainly due to the following factor:

Decompression sickness (DCS) is caused by the formation of bubbles from dissolved ine gas (usually nitrogen) during or after ascent (decompression) from a compressed gas dive. Breathing at elevated Pamb results in increased uptake of ine gas into blood and then into tissues. Bubbles may form within tissues themselves, where they cause symptoms by mechanical distraction of pain-sensitive or functionally impoant structures. Ref: Bennett M.H., Mitchell S.J. (2012). Chapter e52. Hyperbaric and Diving Medicine. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.